Alexander the Great's empire covered the modern countries of Turkey, Iran, Iraq, Syria, Greece, Jordan, Israel, Pakistan, Afghanistan, Tajikistan, Egypt and Greece. At the time that Alexander came to be King of Macedonia, he spent the first part of his reign consolidating his power and putting down rebellions. By the time he had been king 2 years, he had already wiped Thebes out of existence and began his march on Hellespont.
It took approximately 10 years for Alexander to take full control of what came to be known as one of the largest empires in world history. After putting Greece completely under his control, his next mission was what is known as Turkey today. Alexander nearly died before he faced the Persian army at Issus due to a possible respiratory illness brought on by swimming in the Cyndus river. If he had died from the illness there, the entire history of the Middle East, Egypt and Mediterranean area would have been much different.
The next major step after Turkey was Alexander's conquest of Egypt, where he was named pharaoh and established the city of Alexandria. From Egypt, he turned north and into modern day Iran and Iraq, which would be the first of the battles he fought as he headed east and deeper into Asia before heading home, where he died of an illness after a banquet. His heirs were killed within a few years, and the empire began to fall apart.